#include<stdio.h>
#include<string.h>
#include <stdbool.h>
bool isAlphanumeric(char c) {
    return (c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z') || (c >= '0' && c <= '9');
}

bool isPalindrome(char *s) {
    int left = 0, right = strlen(s) - 1;

    while (left < right) {
        // 跳过非字母数字字符
        while (left < right && !isAlphanumeric(s[left])) {
            left++;
        }
        while (left < right && !isAlphanumeric(s[right])) {
            right--;
        }

        // 将大写字母转换为小写字母
        if (tolower(s[left]) != tolower(s[right])) {
            return false;
        }
        
        left++;
        right--;
    }
    return true;
}


int main()
{
    printf("%d\n",5/2);
}